Cardiopulmonary resuscitation (CPR) is a well known and valuable method of first aid. CPR is used to resuscitate people who have suffered from cardiac arrest after heart attack, electric shock, chest injury and many other causes. During cardiac arrest, the heart stops pumping blood, and a person suffering cardiac arrest will soon suffer brain damage from lack of blood supply to the brain. Thus, CPR requires repetitive chest compression to squeeze the heart and the thoracic cavity to pump blood through the body. Very often, the victim is not breathing, and mouth to mouth artificial respiration or a bag valve mask is used to supply air to the lungs while the chest compression pumps blood through the body. The methods of providing oxygenated airflow to the lungs and getting rid of Co2 are referred to as oxygenation and ventilation respectively.
It has been widely noted that CPR and chest compression can save cardiac arrest victims, especially when applied immediately after cardiac arrest. Chest compression requires that the person providing chest compression repetitively push down on the sternum of the victim at 100 compressions per minute. CPR and closed chest compression can be used anywhere, wherever the cardiac arrest victim is stricken. In the field, away from the hospital, CPR may be accomplished by ill-trained by-standers or highly trained paramedics and ambulance personnel. The conventional thinking is that The victim's chest is compressed by the rescuer, ideally at a rate and depth of compression in accordance with medical guidelines, e.g., the American Heart Association (AHA) guidelines.
Traditional CPR is performed by active compression of the chest by direct application of an external pressure to the chest. This phase of CPR is typically referred to as the compression phase. After active compression, the chest is allowed to expand by its natural elasticity which causes expansion of the patient's chest wall. This phase is often referred to as the relaxation or decompression phase. Such expansion of the chest allows some blood to enter the cardiac chambers of the heart. The procedure as described, however, is inefficient to oxygenate the body. Consequently, conventional CPR also requires periodic ventilation of the patient. This is commonly accomplished by a mouth to-mouth technique or by using positive pressure devices, such as a self-inflating bag which delivers air through a mask, an endotracheal tube, or other artificial airway.
In order to increase cardiopulmonary circulation induced by chest compression, a technique referred to as active compression-decompression (ACD) has been developed. According to ACD techniques, the active compression phase of traditional CPR is enhanced by pressing an applicator body against the patient's chest to compress the chest. Such an applicator body is able to distribute an applied force substantially evenly over a portion of the patient's chest. More importantly, however, the applicator body is sealed against the patient's chest so that it may be lifted up to 10% beyond the neutral position to actively expand the patient's chest during the relaxation or decompression phase. The resultant negative intrathoracic pressure induces venous blood to flow into the heart from the peripheral venous vasculature of the patient resulting in better cardiac out put in subsequent compression. Devices and methods for performing ACD to the patient are described in U.S. Pat. Nos. 5,454, 779 and 5,645,552, the complete disclosures of which are herein incorporated by reference.
CPR is often administered in conjunction with other procedures which, taken together, are referred to as advanced cardiac life support (ACLS) for adults and pediatric advance life support (PALS) for children. Most commonly, CPR is administered while the patient undergoes both electrocardiographic monitoring (ECM) and electrical defibrillation. Both ECM and defibrillation require the attachment of electrodes to the patient's chest. The inventors have recognized that the need to attach electrodes can interfere with the ability to administer CPR, particularly the ability to administer manual CPR and give shock to the patient at the same time.